MAPK1 and cancer: β-arrestins mediates ERK activation in clathrin-coated pits (DeFea et al., 2000). β-arrestins act as a scaffolds that bind C-Raf, MEK, and ERK and direct signaling to the cytosol preventing ERK translocation to the nucleus (DeWire et al., 2007; Shenoy and Lefkowitz, 2011) Dysregulation of β-arrestins expression, localization, or phosphorylation is associated with more aggressive cancer phenotypes and poorer prognosis in breast, prostate, lung, brain, and hematological tumors (Sobolesky and Moussa, 2013).